Assessment of EchoMRI-AH™ vs. Dual-energy X-ray Absorptiometry (DXA) to Measure Human Body Composition

BACKGROUND: The sensitivity to detect small changes in body composition (fat mass and fat-free mass) largely depends on the instrument's precision. We compared EchoMRI-AH™ and DXA (Hologic QDR-4500A) for estimating fat mass in 301 volunteers. METHODS: Body composition was evaluated in 136 males and 165 females with a large range of body mass index (19–49 kg/m(2)) and age (19–91 y old) using DXA and EchoMRI-AH™. In a subsample of 13 lean (BMI=19–25 kg/m(2)) and 21 overweight/obese (BMI>25 kg/m(2)) individuals, within-subject precision was evaluated from repeated measurements taken within one hour (n=3) and one-week apart (mean of three measurements taken on each day). RESULTS: Using Bland-Altman analysis, we compared the mean of the fat mass measurements vs. the difference in fat mass measured by both instruments. We found that EchoMRI-AH™ quantified larger amount of fat vs. DXA in non-obese (BMI<30 kg/m(2); [1.1, CI(95):-3.7 – 6.0 kg]) and obese (BMI≥30 kg/m(2); [4.2, CI(95):-1.4 – 9.8 kg]) participants. Within-subject precision (coefficient of variation %) in fat mass measured within one hour was remarkably better when measured by EchoMRI-AH™ than DXA (<0.5% vs. <1.5%, respectively; p<0.001). However, one-week apart within-subject variability showed similar values for both instruments (<2.2%; p=0.15). CONCLUSIONS: EchoMRI-AH™ yielded greater fat mass values when compared with DXA (Hologic QDR-4500A), particularly in fatter subjects. EchoMRI-AH™ and DXA showed similar one-week apart precision when fat mass was measured both in lean and overweight/obese individuals.